I recently had to downgrade gnupg to 2.3.6 after an update because it stopped working with my YubiKey:
```
Aug 31 11:45:58 gpg-agent[40089]: scdaemon[40089]: detected reader 'Yubico YubiKey OTP+FIDO+CCID 00 00'
Aug 31 11:45:58 gpg-agent[40089]: scdaemon[40089]: DBG: Curve with OID not supported: 2b06010401da470f01
Aug 31 11:45:58 gpg-agent[40089]: scdaemon[40089]: no supported card application found: Card error
```
`2b06010401da470f01` seems to be an OID for `Ed25519` curve.
this is [[ https://github.com/nazarewk-iac/nix-configs/blob/9085c484440ac4c381b09758f10bbc83f24bdb63/modules/hardware/yubikey/default.nix#L16-L28 | my scdaemon.conf ]] :
```
nazarewk@nazarewk-krul ~ % cat ~/.gnupg/scdaemon.conf
pcsc-shared
# disable-ccid to make YubiKey work
# - https://support.yubico.com/hc/en-us/articles/360013714479-Troubleshooting-Issues-with-GPG
# - https://dev.gnupg.org/T5451
disable-ccid
# PIN caching fix
# - https://github.com/drduh/YubiKey-Guide/issues/135
# - https://dev.gnupg.org/T3362
# fix from https://dev.gnupg.org/T5436#148656
disable-application piv
nazarewk@nazarewk-krul ~ % cat ~/.gnupg/gpg-agent.conf
pinentry-program /nix/store/0y1vlxssvxv4j3q922n8mjwayihvqyh9-pinentry/bin/pinentry
```